Fuse construction



1958 G. R. MCCLOUD 2,847,535

FUSE CONSTRUCTION Filed Dec. 9, 1955 INVENTOR. Gamma R. M CLQUD ATTORNEY FUSE CONSTRUCTION George R. Mc'Cloud, Cutlahy, Wis., assignor to McGraw- Edison Company, a corporation of Delaware Application December 9, 1955, Serial No. 552,147

2 Claims. (Cl. 200-414) This invention relates to a circuit interrupter of the expulsion fuse type.

in circuit interrupters of the type hereinabove mentioned, such as that shown in the patent to William O. Schultz et al., No. 2,310,466, of February 9, 1943, for Fuse Construction, assigned by mesne assignment to the same assignee as the present invention, and in the type shown in my copending application S. N. 490,465, filed February 21, 1955, for Fuse Construction, also assigned to the same assignee as the present invention, an expulsion fuse of the drop out type was provided and was associated with a manually operable lever, such as one capable of operation through the medium of a switch stick, and so arranged that when it was desired to open the circuit manually, force was applied to the lever to cause mechanical rupture of the fuse link at its weakest point. Thereafter, expulsion action tok place and the fuse tube was cleared. Also, under normal conditions when an overload occurred, the expulsion fuse would operate in the customary manner and rupture under overload and clear itself.

in devices of this type considerable difficulty has been experienced in clamping the fuse link, that is to say, the leader portion of the fuse link to the lower contact means. There was a tendency for the fuse link to slip unless the clamping means was very tight.

In the present invention one of the specific objects is to provide clamping means for the fuse link in a device of the general type hereinabove outlined which is so constructed that as the tension on the fuse link increases, the clamping pressure exerted on the fuse link also increases in an automatic manner.

In greater detail, further objects are to provide an expulsion fuse construction in which a lever is pivoted to the lower contact of the fuse tube adjacent the open end thereof, and in which this lever carries a wedge which erves to clamp the fuse link between itself and the lever so that when the lever is externally manipulated by manual means to rupture or break the fuse link within the expulsion fuse tube under load conditions, there will be no chance of slipping of the fuse link with reference to the lever.

Embodiments of the invention are shown in the accompanying drawings in which:

Figure l is a side view of the fuse tube and the associated structure removed from the stationary portion thereof and showing one form of the invention.

Figure 2 is a fragmentary view to the lower portion of Figure 1 drawn to a slightly enlarged scale.

Figure 3 is a fragmentary sectional view on the line 33 of Figure 1.

Figure 4 is a view roughly corresponding to Figure 2 showing a further form of the invention, such view being partly broken away and partly in section.

Figure is a fragmentary sectional view on the line 5-5 of Figure 4.

Figure 6 is a fragmentary sectional view on the line 66 of Figure 7 showing a further form of the invention.

nited States Patent 0 "ice Figure 7 is a fragmentary side elevation of the structure shown in Figure 6.

Referring to Figure l of the drawing it will be seen that an expulsion fuse tube 1 has been shown. This expulsion fuse tube is open at its bottom end and closed at its upper end and is provided with upper and lower contact means indicated generally by the reference charac' rs 2 and 3 which are rernovably received in removable contact means in accordance with the usual practice and as shown in my above noted application. The upper contact 2 is provided with an upwardly projecting portion 4 closed by closure cap 5. These members 4 and 5 are of metal, and the fuse tube 1 is of fiber or other suitable insulating material in accordance with the usual practice.

The lower contact means 3 is formed of metal throughout and includes a ferrule like member 6 which rigidly receives the lower end of the fiber tube l. This member 6 is provided with an integral switch stick eyelet portion 7, and has a lever or member 8 pivoted thereto as indicated at 9. The member 8 is provided with a switch stick receiving outwardly projecting arm 16 which is adapted to be pulled downwardly to rotate the member 8 and break the fuse link indicated generally at 11 within the fuse tube 1.

The fuse link 11 is provided with a flexible leader 7 portion 12 and a reduced fusible section 13 provided with a strain wire 14 and an upper disk 15 which is clamped to the upper contact means 2 by means of the screw cap 5. The lower portion of the leader 1?; projects outwardly and is secured to a rocking fuse link lever 16 which is pivoted at 17 to the extension 7 of the ferrule 6.

The lever 16 may be called a fuse link receiving or fuse link breaking member and it will be seen that the fuse link extends over the free outer end of the lever 16. This free outer end is provided with a lip like portion 18 which bears against the cam portion or cam portions 19 of the lever 8, the lever 8 being bifurcated straddling the ferrule portion 6.

The lever 16 is provided with a threaded stud 2t) which is rigid with the lever 16 on which is screwed the clamping thumb nut 21.

The thumb nut 21 slidably carries a we member with the small end of the wedge extending towards the fuse tube, or in other words, towards the outer end of the fuse link breaking lever 16. The thumb nut and Wedge securely clamp the leader portion 12 of the fuse link between the wedge 22 and the opposed surface of the lever 16 as shown more clearly in Figures 2 and 3. The wedge or wedging structure 22 is provided with a se rated or roughened inner surface for engaging the fuse link leader 12. The fuse link leader may extend outwardly as shown in Figure 3 or may be wrapped around the stud 26. The wedge 22 is provided with integral arms 23 which are turned inwardly and overhang a flange 24 formed as an integral portion of the thumb nut 21. It is to be noted that the wedge 22 is slotted as indicated at 25' and is provided with a pin 26 which is received within a slot 27 formed in the lever 16.

The fuse links are sometimes provided with a double leader in which case the two sections of the leader would be located on opposite sides of the stud 20. This construction is not shown since it is so well known.

If desired a resilient or spring washer 28 may be interposed between the thumb nut and the wedge 22 as shown in Figures 4 and 5.

Further, if desired the thumb nut may be replaced by means of a bifurcated lever 29, see Figures 6 and 7 and the lever 16' corresponding to the fuse link receiving lever 16 would be provided with a rectangularly shaped projectin stud 3b to which the bifurcating lever 29 is pivoted. This bifurcated lever is provided With a cam portion 31 which engages the wedge member 22" so that when the lever 29 is rocked in a counterclockwise direction as viewed in Figure 7 it will force the wedge member 22" against the leader 12 of the fuse link.

It is to be noted that the wedge member 22" of Figures 6 and 7 is provided with a slot 32 through which the stud 30 projects and is provided with a pin 26 corresponding to the pin 26 of the first form of the invention. Further it is to be noted that the lever 16 is provided with a slot 27 corresponding to the slot 27 of the first form of the invention.

It will be seen that several different forms of the invention have been shown in each of which locking means that grips the lower or projecting end of the fuse link has been shown which automatically increases the grip on the fuse link as strain is imposed on such link. This is particularly useful in fuse constructions of the type shown where mechanical means are employed which when manually manipulated mechanically break the fuse link within the fuse tube so as to secure the expulsion action.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim:

1. An expulsion fuse device comprising an expulsion fuse tube having an open end, contact means adjacent opposite ends of said tube, the contact means adjacent the open end of said tube including a lever pivoted thereto and having a free end, a fuse link Within said tube joining said contact means and extending out of the open end of said tube and over the free end of said lever, said lever having a stud projecting therefrom, a wedge carried by said lever and having a slot through which said stud extends, said fuse link being positioned between said wedge and said lever, a releasable lever carried by said stud and located on the outer side of said wedge and having cam means for providing pressure against said wedge, said wedge having its thin edge projecting towards the free end of said first mentioned lever and slideable in the direction in which the thin edge of the wedge points, and manually operable means for rocking said first mentioned lever to break said fuse link within said fuse tube.

2. An expulsion fuse device comprising an expulsion fuse tube having an open end, contact means adjacent opposite ends of said tube, the contact means adjacent the open end of said tube including a lever pivoted thereto and having a free end, a fuse link within said tube joining said contact means and extending out of the open end of said tube and over the free end of said lever, said lever having a support projecting therefrom, a Wedge carried by said lever and having a slot through which said support extends, said fuse link being positioned between said wedge and said lever, a releasable lever carried by said support and located on the outer side of said wedge and having cam means for providing pressure against said wedge, said wedge having its thin edge projecting towards the free end of said first mentioned lever and slideable in the direction in which the thin edge of the Wedge points, said cam means consisting of a cam rotatably mounted on said support having a rounded portion bearing against said Wedge and having a radius which increases in length as the thicker portion of said wedge is approached, and manually operable means for rocking said first mentioned lever to break said fuse'link within said fuse tube.

References Cited in the file of this patent UNITED STATES PATENTS 310,390 Deibert Jan. 6, 1885 962,620 Butler June 28, 1910 1,656,113 Herman Jan. 10, 1928 2,291,646 Ramsey Aug. 4, 1942 2,310,466 Schultz et al. Feb. 9, 1943 2,433,906 Husted Jan. 6, 1948 

